ET, phone SETI@home - In only one week since the release of free
SETI@home software nearly 300,000 computers have contributed 1100
years of CPU time to the search for extraterrestrial life. Read
this article to find out how you can join the search, to discover
how SETI@home works, and to learn more about the giant radio
telescope that collects the data for your home computer.

University of California-Berkeley

11/25/98

Searching for ET from home

UC Berkeley launches project to draw public
into the search for extraterrestrial intelligence

By Robert Sanders, Public Affairs

BERKELEY -- One hundred lucky pioneers will get the chance of a lifetime
this month -- the opportunity to participate in a unique search for
extraterrestrial intelligence from their desktop computer.

These one hundred will test a one-of-a-kind computer program called
SETI@home
that allows a desktop PC to analyze radio data from space in search of
intelligent signals. If all goes well, the finished product will roll out
next April for 100,000-plus people who have already signed up to participate.

The computer program is essentially a screen saver that kicks in when your
desktop computer is idle, and crunches data collected from a radio dish in
Puerto Rico.

"SETI@home is a way of harnessing all the idle computers to increase our
computing capacity and our chance of finding extraterrestrials," said
SETI@home project scientist Dan Werthimer, a research physicist at UC
Berkeley's Space Sciences Laboratory.

SETI@home -- named after the acronym for the search for extraterrestrial
intelligence, SETI -- is a way for UC Berkeley's SETI physicists to more
thoroughly analyze the data they receive daily from their ongoing survey of
the sky using the large radio dish at Arecibo, Puerto Rico. This 20-year-old
search, which piggybacks on the Arecibo telescope, is called SERENDIP IV --
the fourth incarnation of an instrument designed to Search for
Extraterrestrial Radio Emissions from Nearby Developed Intelligent
Populations.

Unfortunately, the computer capacity available to SERENDIP is sufficient to
look for only the most obvious signals from extraterrestrial civilizations,
Werthimer said.

"In terms of science, SERENDIP is very powerful, but it looks for a very
restricted class of signal," said Werthimer. "SETI@home does an exceptionally
good job of analyzing a small band of signals very thoroughly."

The radio data is broken down into small chunks -- typically a range of
wavelengths -- through which the screen saver program can search for patterns
that may indicate a deliberate broadcast from a distant civilization.

"You can download enough data through the internet in five minutes to keep
the computer analyzing for several days," said computer scientist David
Anderson, project director and a long-time volunteer with the project. "The
computer then sends back a summary of the interesting stuff it found, and
gets another chunk of data."

As the computer works away at the data, the computer screen displays a
three-dimensional graph charting the signal analysis.

Anderson developed the screen saver program that crunches the data, now
available only for PCs. He currently is developing versions for Macintosh,
Unix, Linux and other systems.

"The point is to get the bugs out of the software so we are ready to go for
100,000 people in April," Werthimer said.

The SETI@home project is the first "distributed computing" project to offer
the general public the opportunity to participate in important research.
Distributed computing is a way of breaking down a problem requiring lots
of computation into small chunks that can be done by many small computers
distributed anywhere in the world.

"Ours is the first that actually does a useful computation and sends data
both ways through the pipe," Anderson said.

The type of data coming from SERENDIP is particularly suitable for
distributed computing, Anderson said, though other major scientific
projects -- drug discovery, for example -- might also be candidates. The
main requirement is number crunching, or in computer jargon, CPU (computer
processing unit) time.

"Projects suitable for distributed computing are those that are very CPU
intensive with not a lot of data to transfer," Anderson said. "But there
are many such projects, which may create a future market in CPUs."

SETI@home has been building to this point for several years, mostly with
the help of volunteers. What finally got it off the ground, however, was an
infusion of money from the Planetary Society, which donated $50,000, and
Paramount Studies, which donated another $50,000 and is tying the project
to the launch of its new movie, "Star Trek: Insurrection," December 11. Sun
Microsystems also has donated computer equipment to SETI@home.

With the publicity generated by these two donors, the project is getting a
thousand new sign-ups each day, Werthimer said.

The SERENDIP IV instrument on the 1,000-foot diameter Arecibo dish looks at
radio signals in the "water hole," an area of the spectrum identified as a
possible region where advanced civilizations might broadcast a signal. It
is located to either side of the 21 centimeter wavelength, the wavelength
of light absorbed by water molecules in space.

SERENDIP records signals in a band around the water hole and stores them on
magnetic tape, which is expressed to UC Berkeley for analysis.
The more detailed analysis that can be done by the SETI@home screen saver
will look for unusual patterns that are too complex and time consuming for
the SERENDIP project to attempt.

Whatever interesting signals may turn up from SETI@home must be checked by
people like Werthimer to make sure they are not due to radio interference
from Earth or orbiting satellites.

"We're not asking people to call the press when they see a spike on the
screen," Werthimer said. "We get strong signals all the time and have to
sift through them."